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  • Comparative Studies. Non-European Languages/Literatures  (17)
  • 1
    Online Resource
    Online Resource
    The effects of rail support stiffness on railway rolling noise
    Acoustical Society of America (ASA) ; 1999
    In:  The Journal of the Acoustical Society of America Vol. 105, No. 2_Supplement ( 1999-02-01), p. 947-947
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 105, No. 2_Supplement ( 1999-02-01), p. 947-947
    Abstract: Rolling noise from trains is radiated by both wheel and track vibrations, the track being dominant in many cases. The stiffness of the rail fastener system, especially the elastomeric rail pad usually inserted between the rails and the sleepers, has a significant influence on the noise emitted by the track. Railways are increasingly using softer pads to reduce potential damage to sleepers and ballast. Softer pads decouple the rail from the sleeper. This reduces the noise from the sleeper but also reduces the decay of vibration with distance along the rail and hence leads to an increase of the noise radiated by the rail. The paper describes experimental and theoretical work to investigate the influence of pad stiffness on the dynamic and acoustic behavior of track. The vibrational behavior has been measured on a dedicated 36-m section of railway track, with different types of rail pad installed. The results are compared with predictions using theoretical models of the track behavior. This allows the effective pad stiffness and damping to be determined, laboratory measurements also being available for comparison. The attenuation of vertical and lateral vibration along the track is measured in order to estimate the effect on radiated noise.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.425733
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1999
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
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    Auditory Threshold at 125 Hz as a Function of Signal Duration and Signal Filtering
    Acoustical Society of America (ASA) ; 1971
    In:  The Journal of the Acoustical Society of America Vol. 49, No. 6B ( 1971-06-01), p. 1897-1899
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 49, No. 6B ( 1971-06-01), p. 1897-1899
    Abstract: Ten experienced listeners, eight males and two females, whose hearing sensitivity was within normal limits, participated in a study concerned with an assessment of auditory threshold for a 125-Hz stimulus as a function of stimulus duration and low-pass filtering of the test stimulus. Thresholds were obtained with a Békésy-type tracking procedure for six stimulus durations (5, 10, 20, 50, 100, 200 msec) in conjunction with three filtering conditions (unfiltered—UNFIL; 200-Hz low pass—LP-200; 150-Hz low pass—LP-150). Spectral analysis of the stimuli for each duration and filtering condition was performed. Temporal integration occurred for a 125-Hz stimulus during the LP-200 and LP-150 conditions but not when the stimulus was unfiltered (UNFIL). The LP-150 condition resulted in an average integration of 11.5 dB/decade between 5 and 200 msec and the average integration for the LP-200 condition was 8.6 dB/decade. Thresholds over the 5- to 200-msec range for the UNFIL condition did not vary by more than 1 dB, thus indicating the absence of temporal integration. It was inferred that temporal integration occurs for low-frequency stimuli when the spread of energy toward the higher more sensitive frequency region of the auditory area is limited by low-pass filtering.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.1912599
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1971
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  • 3
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    Online Resource
    A feasibility study on the low probability of intercept sonar.
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 127, No. 3_Supplement ( 2010-03-01), p. 1998-1998
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 127, No. 3_Supplement ( 2010-03-01), p. 1998-1998
    Abstract: The feasibility of low probability of intercept for sonar is explored. Using a noise-like active sonar signal, the transmitter (platform) employs a matched filter for echo detection while the target is assumed to use an energy detector. Decision statistic distributions are developed and detection performances are compared with a previous work (Gaussian distribution assumed). We then explore the detection advantage the platform can achieve by evasive on-off keying and by optimization of transmitted power. A favorable operating region of the platform in the (low power, small range) region of the (range, power) plane is identified. This suggests that the platform should start detection using a low-power probing signal, increasing power until a reliable detection rate is first achieved while ensuring that the detection rate at the target does not exceed a specified level. Second part of the feasibility study is about covert range estimation. Two matched-filter based algorithms were developed for the platform to obtain credible range estimations while ensuring the target fails to detect the platform. A platform-target encounter scenario was designed for detailed waveform-based Monte Carlo simulation. Characterization of variables in the model was performed to show the feasible conditions of covert range estimation. [Work sponsored by ONR, ULI.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3385181
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
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  • 4
    Online Resource
    Online Resource
    Effect of measurement parameters on acoustic reflex thresholds
    Acoustical Society of America (ASA) ; 1985
    In:  The Journal of the Acoustical Society of America Vol. 77, No. S1 ( 1985-04-01), p. S105-S105
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 77, No. S1 ( 1985-04-01), p. S105-S105
    Abstract: Estimates of acoustic reflex thresholds (ARTs) may differ by 5 dB or more between lowest (“best”) and highest reported values. These discrepancies are likely due to differences in measurement characteristics (sensitivity, probe tone level, display mode, and temporal response) of acoustic immittance instruments in addition to criteria used for judgment of threshold and normal threshold variability. Continued development of ART measurement methods for clinical evaluation is hampered by such disparities. We therefore studied the effects of selected measurement parameters on ARTs. Contralateral acoustic-reflex thresholds were measured in ten subjects with normal hearing sensitivity using a digital acoustic-immittance instrument that allowed discrete changes in measurement parameters. In the first experiment, probe microphone sensitivity was varied in four steps from low to high values, in the second experiment probe tone (226 Hz) level was varied from 72 to 84 dB in 4-dB steps, and in the third experiment effective measurement time constant was varied from 8.8 to 141.6 ms in 8.8-ms steps. Three independent judgments of ARTs were made from plots of responses to a 1000-Hz tone and broadband noise and means of the judgments were used for analysis. Results indicate that instrument measurement parameters can affect ARTs and should be accounted for. [Research supported by Rehabilitation Research and Development Service of the Veterans Administration.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2022146
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1985
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  • 5
    Online Resource
    Online Resource
    Perstimulatory adaptation of acoustic reflex in normally hearing subjects
    Acoustical Society of America (ASA) ; 1981
    In:  The Journal of the Acoustical Society of America Vol. 70, No. S1 ( 1981-11-01), p. S71-S72
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 70, No. S1 ( 1981-11-01), p. S71-S72
    Abstract: This was an investigation of acoustic-reflex adaptation in ten adults in each age decade between 20 and 79 years. Reflex-activating stimuli, presented by earphone to the ear contralateral to the acoustic-immittance probe, were four tones (0.5, 1.0, 2.0, and 4.0 kHz) and two filtered noises. Sound pressure levels were +5, +10, +15, and +20 dB re: acoustic-reflex threshold. Stimulus duration was 60 s. Reflex responses were measured with both components of aural acoustic admittance. Custom software was written for automated digitization, storage, quantification, and plotting of the responses. Statistical analyses of conductance and susceptance data included static acoustic admittance, acoustic-reflex threshold. maximum amplitude of reflex, rate of adaptation, and shift of baseline during reflex activation. Adaptation rate was highest for the 4.0- and 2.0-kHz activators and varied with stimulus level. Comparison of multiple regressions revealed age-related trends in measures of adaptation. [Work supported by VA-RER & D.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2019013
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1981
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  • 6
    Online Resource
    Online Resource
    Numerical investigation of aeroacoustic characteristics of a circular cylinder in cross-flow and in yaw
    Acoustical Society of America (ASA) ; 2015
    In:  Journal of the Acoustical Society of America Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2224-2224
    Details
    In: Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2224-2224
    Abstract: It is well known that aerodynamic noise becomes dominant when the speed of high-speed trains exceeds about 300 km/h. The pantograph is one of the main aerodynamic noise sources, particularly in the presence of noise barriers which shield the sources on the lower part of the train more effectively. The pantograph consists of a number of slender bodies with different cross-sections. In the current research, the aerodynamic characteristics of a circular cylinder have been investigated through computational fluid dynamics simulations using a Delayed Detached-Eddy Simulation model. Then the aeroacoustic behaviour has been predicted by using Ffowcs Williams-Hawkings equation. Simulations have been carried out for various speeds, resulting in a wide range of Reynolds number, which includes subcritical, critical, and supercritical flow states. The results have been compared with experiments and give good agreement. As the pantograph arms are inclined to the flow, the effect of yaw angle is analyzed in this paper and the effect on vortex-shedding frequency and noise level is determined. Moreover, it is demonstrated that the critical Reynolds number, which determines the beginning of the critical flow state, is affected by the yaw angle. In addition, considering the high turbulence intensity on the train roof, a turbulent inflow with different levels of intensity has been considered and the results will be presented.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4920105
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
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  • 7
    Online Resource
    Online Resource
    Analog versus digital measurement of aural acoustic immittance
    Acoustical Society of America (ASA) ; 1983
    In:  The Journal of the Acoustical Society of America Vol. 73, No. S1 ( 1983-05-01), p. S79-S79
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 73, No. S1 ( 1983-05-01), p. S79-S79
    Abstract: Static and dynamic measurements of aural acoustic immittance (AAI) were made in couplers and in real ears using two analog and two digital instruments. Comparisons were made among instruments, and between the analog and digital approaches, with regard to accuracy, range, reliability, and validity (proper resolution of immittance components, measurement of real-ear immittance, stability of calibration in hard-walled couplers) of measures. The influence of environmental parameters (temperature, barometric pressure, shape of test cavity) and temporal constraints (total system latency, hysteresis) was also investigated. Relative advantages and disadvantages of the two measurement approaches for clinical determination of pressure-immittance functions and the acoustic reflex were cited. Results indicated promise for implementation of digital AAI testing, particularly with regard to dynamic measurements. [Work supported by RR and D of Veterans Administration.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2020561
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1983
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  • 8
    Online Resource
    Online Resource
    Influence of ground impedance on the sound radiation of a railway sleeper
    Acoustical Society of America (ASA) ; 2015
    In:  Journal of the Acoustical Society of America Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2234-2234
    Details
    In: Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 137, No. 4_Supplement ( 2015-04-01), p. 2234-2234
    Abstract: A railway track consists of rails attached to sleepers (cross ties) which are laid in ballast. The sleeper provides support for the rail and transfer loads to the ballast and subgrade. Due to the wheel/rail interaction the rail is induced to vibrate and this vibration is transmitted to the sleepers; both the rail and the sleepers radiate sound. Existing models used to predict the sound radiation from the sleeper consider this to be completely embedded in a rigid ground; in reality, however, the sleeper is surrounded by, or embedded to some extent, in the ballast. It is therefore necessary to take these conditions into account in order to obtain a more realistic model. This paper investigates the influence of the ground in close proximity to the sleeper on its sound radiation. A 1/5 scale concrete sleeper is analyzed by using the boundary element method in 3-D. Ground absorption is introduced in terms of its acoustic impedance using the Delany-Bazley model and its effects on the sleeper radiation are predicted. Finally, the numerical results are validated by experimental results using a 1/5 scale model.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4920152
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
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  • 9
    Online Resource
    Online Resource
    New books in review
    Informa UK Limited ; 1969
    In:  Quarterly Journal of Speech Vol. 55, No. 4 ( 1969-12), p. 440-458
    Details
    In: Quarterly Journal of Speech, Informa UK Limited, Vol. 55, No. 4 ( 1969-12), p. 440-458
    Type of Medium: Online Resource
    ISSN: 0033-5630 , 1479-5779
    URL: Article
    DOI: 10.1080/00335636909382974
    RVK:
    EQ 1000
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 1969
    detail.hit.zdb_id: 2066946-X
    SSG: 7,11
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  • 10
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    Online Resource
    The speed of sound in epoxy resin blends and composites
    Acoustical Society of America (ASA) ; 1982
    In:  The Journal of the Acoustical Society of America Vol. 72, No. S1 ( 1982-11-01), p. S10-S10
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 72, No. S1 ( 1982-11-01), p. S10-S10
    Abstract: Sound speeds in two types of diamine-cured epoxy resin blends were determined as functions of frequency, temperature, and composition, and the feasibility of impedance matching through the addition of microballoon fillers was also demonstrated. A filled resin system based on a diglycidyl ether of poly (propylene glycol) was shown to possess a mass density near 1.0 g/cm3 and propagate sound at speeds near 150 m/s, while a resin system based on a diglycidyl ether of bisphenol A exhibited sound speeds and specific acoustic impedances about twice those of water. Although the incorporation of microballoons slightly increased sound speeds, the corresponding density reductions resulted in a net decrease of the specific acoustic impedance in all instances. [Work supported by NAVSEA 63R.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2019725
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1982
    detail.hit.zdb_id: 1461063-2
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